2. A smooth muscle contraction-stimulating hormone found in the neurohypophysis.
3. A hormone made in the brain that plays a role in childbirth and lactation by causing muscles to contract in the uterus (womb) and the mammary glands in the breast. Animal studies have shown that oxytocin also has a role in pair bonding, mate-guarding, and social memory.
4. A peptide (a compound consisting of two or more amino acids) that is secreted by the hypothalamus and transported to the posterior lobe of the pituitary gland at the base of the brain. Oxytocin is related to another hormone called vasopressin.
5. In pharmacy, a commercial form of this substance, obtained from beef and hog pituitary glands or; especially, by synthesis, and used chiefly in obstetrics to induce labor and to control postnatal hemorrhage.
6. Nasally administered oxytocin appears to generate trust in humans.
In a 2005 study, it was shown that in a risky investment game, experimental subjects given the hormone displayed what the researchers deemed "the highest level of trust" twice as often as the control group who were given placebos.
The same experiment with the subjects told that they were interacting with a computer showed no such reaction, leading to the conclusion that oxytocin was not merely affecting risk-aversion.7. Various anti-stress functions: reducing blood pressure and cortisol levels, increasing tolerance to pain, reducing anxiety.
Oxytocin may play a role in encouraging "tend and befriend", as opposed to "fight or flight", behavior, in response to stress.